The Biology of Human Starvation: Volume I
By Ancel Keys, Josef Brozek, Austin Henschel, Olaf Mickelsen and Henry Longstreet Taylor (The University of Minnesota Press, 1950)
Hang on. Why are you reviewing a book that was first published over 70 years ago?
It’s a fair question.
Well, if you read any of the other features on this site, you’ll see that the name of lead author Ancel Keys crops up a lot, as does his work, in particular the Minnesota Starvation Experiment (MSE). The MSE gave us unparalleled insight into the effects of starvation on the human body and mind, and since there have been no controlled scientific studies into starvation ever since (for obvious ethical reasons), it’s the best tool that we have to truly understand the impact of malnutrition on human beings.
Up until now all my information on the MSE has been received second-hand. I thought it was time to go to the horse’s mouth and read the write-up of the famous study. Admittedly, it was a little daunting. Volume I alone is a hefty tome of over 750 pages, and as I am no scientist I was worried I might find some of the language and concepts tricky. But I wanted to see exactly what the experiment can tell us about starvation and how that relates to the experience of someone with anorexia nervosa. I was particularly keen to find any differences between ‘normal’ starvation (or semi-starvation as Keys is careful to refer to it — the men were fed, just not very much) and anorexia nervosa. If we could find out what’s different about these experiences, I figured, that might give us some clues into the underlying biological cause/s of anorexia.
A full account of human experience with starvation would cover all of history and would penetrate every phase of human affairs. As some scholars have pointed out, the history of man is in large part the chronicle of his quest for food.
The ambition behind this work becomes apparent in these opening sentences. This book is designed to offer understanding into something that has been at the heart of humanity’s experience since the dawn of time — hunger. And it’s purpose is to understand the effects of malnutrition on the human body, the best way to successfully re-nourish someone who has suffered starvation and how to feed people when faced with limited resources.
The real beginning of civilization came with the development of agriculture.
Ancel Keys understood that starvation, or the fear of it, has driven much of human activity throughout our existence, and the ability of humans to manage their own food production marked the start of a more advanced way of living. Having ready access to food allowed us to focus on other things, which incidentally is also how many describe life after anorexia. It is extraordinary to me that so little attention has been paid by scientists to anorexia nervosa because if we could unlock the secrets of this illness, we could perhaps reach a deeper fundamental understanding of human biology.
I was surprised to find that this book does not only contain the results of the MSE. It’s commonly reported that this is the only study into human starvation that we have. But Keys and his co-authors acknowledge the work of many others who went before them. The Biology of Human Starvation looks at existing sources of information, including other studies into starvation in animals and humans; reports on prisoners of war; writings on victims of famine around the globe; and anorexia patients.
More than 100 conscientious objectors volunteered to take part in the MSE and 36 men made the final cut. Among the reasons for applying were: to contribute to scientific knowledge; to see if they could endure starvation; to allay guilt at not joining up; educational opportunities that were offered; and simply, curiosity: what is it like to starve?
The study looked at the effect of semi-starvation on many aspects of human biology, including heart rate, weight, circulation, nitrogen balance, metabolism, even sperm motility. The men subsisted on a diet made up largely of cabbage and turnips, designed to resemble a typical starvation diet. Keys was meticulous in his approach, and the results are reported in impressive detail. In fact, there is far more in the book than can be properly reflected here, but these are my key takeaways:
Psychological Effects
Keys notes that most historical studies failed to look at the psychological effects of starvation. It’s extraordinary that he felt this was important and we are lucky to have the results of his work. Emotional and personality changes became apparent in the second month of the MSE. This is explored in more detail in Volume II, which I plan to read soon.
Feasting
After a period of rehabilitation and restricted re-nourishment, the men were permitted to eat freely. This resulted in a daily intake of several times their normal requirement. In the first week each ate upwards of three times the calories they’d eaten in the starvation phase. Some commented that they were still hungry at the end of very large meals, even though they were unable to ingest more food. All ate snacks in between meals and in the evenings. At weekends, some men ate up to seven times what they’d been allowed during the starvation phase.
I suspect this is what, in anorexia recovery, is often labelled as ‘bingeing’ and viewed as a negative. In fact, as the experiment shows, this is the body’s normal response to food being freely available after starvation. Feast follows famine. Keys notes that this feasting phase did not last for more than a few weeks and then the men started to eat a typical amount of food.
Overshoot
Body fat was looked at in detail. During the controlled phase of rehabilitation, fat was restored faster than body weight in all caloric groups except the lowest. After the men in the MSE reached their pre-starvation weight, they continued to gain. 21 of the men added nine per cent on average. In time the weight returned close to the original value, prior to the experiment. This extra gain was determined to be increased fat storage.
There has been much talk of ‘overshoot’ in anorexia nervosa recovery. This is the idea that a person needs to go beyond their original weight to enable the body and brain to repair. One of the most important elements of Keys’ study, in my opinion, is that it clearly showed that this is what normally happens in recovery from malnutrition. The body lays down fat to protect against future famine. It seems illogical that this shouldn’t be the case in recovery from anorexia nervosa, which is also, of course, recovery from malnutrition. Until this takes place, the body, and crucially the brain, will remain in starvation mode. Why should we expect recovery in the brain when the body has not done what it is meant to do?
On the topic of body fat, Keys notes that it has been universally observed that women withstand semi-starvation better than men, and he suggests this may be because of the larger stores of body fat that women’s bodies have. Perhaps this is one of the reasons why we see anorexia in more women than men, particularly if it is a genetic famine response as has been hypothesised.
BMI
Keys is noted for introducing the much-criticise BMI index, which was based on calculations by Belgian mathematician Adolphe Quetelet. Keys mentions Quetelet in the book, referring to his very primitive formulas and noting that it was based solely on Europeans. Keys was clearly skeptical of the value of this formula as a measure of what a person’s weight should be: It is certain that Quetelet’s values are far from precise even for Europeans.
Thyroid
Keys notes that there is consistent evidence that the human thyroid atrophies during starvation. It is well understood that thyroid problems can cause mental illness. Could the effect on the thyroid be responsible for some of the disturbed thoughts in people with anorexia?
Anaemia
There was a ‘considerable degree of anaemia’ as a result of malnutrition. Anaemia is known to affect brain function, and this can be dramatic, as it was for me. Again, could this be partly responsible for the intrusive thoughts of anorexia? The increase in the volume of blood plasma in one case took the better part of a year to return to pre-starvation levels. This goes to show just how long it can take for the body to reach equilibrium after a period of starvation.
Body temperature
Semi-starvation affects body temperature. The men’s skin became cold to the touch and many showed a mild degree of cyanosis (blue tinge) in the lips and nail beds. Even in July they complained of feeling cold and slept with three woollen blankets.
The metabolism of the men in the MSE was reduced overall, but Keys ponders how much of this can be accounted for by the lowered body temperature of the starving organism… but this again raises a question. What is the mechanism of the reduction in body temperature? I did not find an answer to this question in the book.
Burning Feet Syndrome
This is a curious condition that was recorded in various famine areas, according to Keys. The cause is unclear, but cold foot baths and massage offered little relief of the excruciating pains in the feet that were reported. I have heard people with AN talk about pains in their feet, although this could be accounted for by excessive exercise.
The Senses
Vision was unaffected by semi-starvation, but the Keys’ study showed that hearing actually becomes more acute. This was, he says, statistically highly significant. Keys attributes the effect to less earwax and weight loss, ie a thinning of tissues in the ear.
Allergic Reaction
Keys notes that reduced reactivity to some stimuli have been seen in severely starved men and there are suggestions also that allergic and anaphylactic phenomena are repressed. In some cases eczema and asthma become less troublesome or even disappear. It has been mooted that this could be related to the feeling of well-being that some with anorexia nervosa describe comes with restriction.
Amenorrhea
Keys cites clinical descriptions of hunger in Germany during the First World War. All but one of the women had regular periods even though they were suffering from famine, although he also notes that loss of periods were seen in starving women in the Second World War. Keys comments: Although anorexia nervosa is frequently accompanied by amenorrhea there are still a sufficient number of severely emaciated women who maintain regular menstruation to make any categorical statement hazardous.
Nobody took any notice. Loss of periods was often required for a diagnosis of anorexia nervosa in women in the decades that followed. Absence of menstruation was one of the symptoms listed by the Diagnostic and Statistical Manual of Mental Disorders, the US mental health bible, until 2013.
Sperm
Motility of the sperm in the MSE was reduced by more than 50 per cent of normal at the end of semi-starvation. This was reversed in rehabilitation.
In fact, one of the most striking things about the study is how we are shown time and again that the damage caused by starvation is normally reversed with good nutrition.
The body’s capacity to repair itself never ceases to amaze me.
Differences Between Anorexia Nervosa and ‘Normal’ Starvation
Energy
The men in the MSE became less energetic as their food intake was reduced: Reduction of physical activity is a prominent feature of undernutrition. Keys also states: It is evident that under conditions of famine… the ability to climb, walk long distances or stand for prolonged periods of time will be diminished.
People with anorexia often increase their movement and exercise with restriction, and many will stand or fidget for lengthy periods. In fact, compulsive movement is often a key part of the illness. This seems to be one of the main differences between someone with anorexia and someone with ‘normal’ malnutrition.
However, in the book Keys also discusses the fascinating link between restlessness and hunger. He cites a study into rats which noted that the rats became more active at the time of eating. He also notes that Wada (1922) observed that there was a tendency for movement of the body to occur simultaneously with stomach contractions when hungry. Perhaps the compulsive movement in anorexia nervosa, then, is just an exaggeration of this normal reaction to hunger. If so, it would indicate that the way to stop feeling the need to move compulsively would be to stop being hungry and to eat. As usual, this is the opposite of the message given by anorexia.
Weakness
…is one of the cardinal symptoms of starvation, according to Keys. Of course, this is also true in people with anorexia. But many do describe a feeling of powerfulness which can be intoxicating. All the men in the MSE lost capacity to work during the experiment but all improved with re-nourishment and rehabilitation. In reality, starving makes you weak. Eating makes you strong.
Reduction of Physical Abilities
The MSE showed a loss of strength, speed, gross coordination, fine coordination and endurance. I suspect that most of these are not reduced with the starvation that comes with anorexia nervosa. I certainly have not heard of a loss of fine motor skills, for example, although perhaps any loss is too slight to observe in the real world.
Overall the book is a fascinating read, and it’s impossible not to be struck by how Keys, his team and the men in the experiment rose to the challenge, motivated by a keen curiosity and the nobility of the cause. I have to admit that I skipped some of the more science heavy sections, like the chapters on biochemistry, but most of this work is accessible to a non-scientist like me.
The Biology of Human Starvation: Volume I is a comprehensive account of an ambitious piece of work and remains relevant 70 years on. It is an invaluable resource for anyone studying eating disorders and contains important findings, such as overshoot and feasting, that should be routinely reflected in treatment. Anyone with an interest in anorexia nervosa, or indeed eating disorders in general, is indebted to Ancel Keys, the other researchers and those 36 selfless men who starved for science.